The present invention relates to a compressed gas filled circuit breaker of the electromagnetic repulsion type in which a capacitor discharge current flowing through drive coils exerts an electromagnetic repulsive force on movable switch contacts to break the circuit.
The conventional circuit breaker of this type employs an insulator construction, and the energy stored in the capacitor for driving the contacts must be supplied through an insulating transformer from the energy source on the ground side of the breaker system. Also, the control signal for discharging the capacitor is transmitted by a photoelectric signal from the ground side to the high voltage side.
It is well known that insulating transformers are expensive, and this disadvantage as well as the large size thereof becomes more severe when the rated voltage is high because the number of connections is correspondingly increased. Further, the photo-electric system through which the control instruction is transmitted and converted is also expensive.
Recently, a circuit breaker employing a tank type of structure has been proposed. Such devices have anti-shock properties and high durability due to the use of SF.sub.6 gas or the like which causes rapid arc extinction.
It has been attempted to combine the former system, using an insulating transformer, with such a tank type of gas filled circuit breaker in order to obtain the advantages of the latter. However, the incorporation of an insulating transformer in the tank type gas filled circuit breaker has been difficult. It is very difficult to transmit energy to the high potential side because the insulating transformer is much larger than the tank. Also, since the portion for controlling the discharge of the capacitor is positioned in the high potential side and hence inside the tank, the maintenance thereof is difficult. On the other hand, should the energy be derived from the tank, high voltage bushings are required.